Thorium Molten Salt System Using Internally Generated Proton-Induced Neutrons

ABSTRACT

A method of generating power using a Thorium-containing molten salt fuel is disclosed. One example of the disclosed method includes the steps of providing a vessel containing a molten salt fuel, the molten salt fuel comprising Thorium and at least one salt containing a nucleus capable of interacting with a proton of sufficient energy to produce a (p, n) reaction resulting in the generation of a neutron at a first energy level and generating a proton beam externally to the vessel, where the externally generated proton beam being of an energy level sufficient to interact with the at least one salt in the vessel to produce a (p, n) reaction resulting in the generation of a neutron at the first energy level. In the example, the externally generated proton beam is directed into the vessel such that at least some protons forming the beam will interact with an atom forming a part of the at least one salt contained in the vessel to causing interaction between the externally generated proton beam and the at least one salt contained in the vessel to produce (p, n) reactions resulting in the generation of neutrons within the vessel and an absorption reaction involving the generated neutrons and Thorium within the vessel. Neutrons generated within the vessel through the (p, n) reactions caused by the externally generated proton&#39;s interaction with the at least one salt are utilized to produce a fission reaction where the fission reaction increases. the heat content of the molten salt within the vessel. In the example, a heat exchanger is used to extract heat from the molten salt within the vessel and power is generated from the extracted heat.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a Division of U.S. patent application Ser. No.16/554,264, titled, “Thorium Molten Salt System for Energy GenerationUsing Internally Generated Proton-Induced Neutrons,” which is aContinuation of U.S. Patent application Ser. No. 16/517,195, titled,“Thorium Molten Salt System for Energy Generation,” filed on Jul. 19,2019, which is a Continuation of U.S. patent application Ser. No.16/517,096, titled, “Thorium Molten Salt Assembly for EnergyGeneration,” also filed on Jul. 19, 2019. The disclosures of allreferenced applications are hereby incorporated by reference in theirentireties.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not applicable.

REFERENCE TO APPENDIX

Not applicable.

BACKGROUND OF THE INVENTION Field of the Invention

The inventions disclosed and taught herein relate generally to a systemfor generating power using a Thorium-containing liquid molten salt fueland, more specifically, an accelerator-driven Thorium molten salt systemfor generating process heat and/or electricity resulting from nuclearfission reactions.

Description of the Related Art

Attempts have been made to provide an accelerator-driven system for thegeneration of energy using fuel material containing Thorium. To date,such systems have primarily been focused on the use of a solid or moltenlead (or other heavy metal) spallation target to generate neutrons usedto initiate or sustain nuclear fission reaction and fuel initiallycomprising of mixtures of Plutonium and Thorium. Examples of suchsystems are discussed below.

Ashley, Coats et. al, “The accelerator-driven Thorium reactor powerstation,” Energy, Vol. 164, Issue EN3 at 127-135 (August 2011 Issue)discusses an accelerator-driven Thorium reactor in which a particleaccelerator injects high-energy particles into a molten lead target torelease neutrons via the spallation process. The article indicates thata fissile starter, such as Plutonium from spent fuel, is required, andthat the core of the system includes a series of fuel pins, eachcontaining mixed-oxide pellets comprised of Plutonium and Thorium. Asimilar system is disclosed in Ludewig and Aronson, “Study of Multi-BeamAccelerator Driven Thorium Reactor” (March 2011).

U.S. Patent Application Publication No. US2013/0051508, “AcceleratorDriven Sub-Critical Core” purports to disclose “a fission powergenerator [that] includes a sub-critical core and a plurality of protonbeam generators” where the generated proton beams “via spallation”generate neutrons for use in the system.

The use of heavy metal spallation targets poses several challenges asdoes the use of fuel initially containing Plutonium or Uranium.

The present inventions are directed to providing an enhanced system forenergy generation providing benefits over, and overcoming shortcomingsof, the systems and methods discussed in the materials referenced above,and other existing systems.

BRIEF SUMMARY OF THE INVENTION

A brief non-limiting summary of one of the many possible embodiments ofthe present invention is:

A method of generating power using a Thorium-containing molten saltfuel, the method including the steps of: providing a vessel containing amolten salt fuel, the molten salt fuel comprising Thorium and at leastone salt containing a nucleus capable of interacting with a proton ofsufficient energy to produce a (p, n) reaction resulting in thegeneration of a neutron at a first energy level; generating a protonbeam externally to the vessel, the externally generated proton beambeing of an energy level sufficient to interact with the at least onesalt in the vessel to produce a (p, n) reaction resulting in thegeneration of a neutron at the first energy level; directing theexternally generated proton beam into the vessel such that at least someprotons forming the beam will interact with the nucleus forming a partof the at least one salt contained in the vessel; causing interactionbetween the externally generated proton beam and the at least one saltcontained in the vessel to produce (p, n) reactions resulting in thegeneration of neutrons within the vessel; utilizing neutrons generatedwithin the vessel through the (p, n) reactions caused by the externallygenerated proton's interaction with the at least one salt to produce anabsorption reaction involving the generated neutrons and Thorium withinthe vessel; utilizing neutrons generated within the vessel through the(p, n) reactions caused by the externally generated proton's interactionwith the at least one salt to produce a fission reaction involving thegenerated neutrons, the fission reaction increasing the heat content ofthe molten salt within the vessel; utilizing a heat exchanger to extractheat from the molten salt within the vessel; and generating power fromthe extracted heat

Additionally, or alternatively, a method in accordance of with thepresent disclosure may include the steps of: producing a proton beam,wherein an average energy level of the protons comprising the protonbeam is at least 2.4 MeV; providing a molten salt assembly comprising amain body, a lid, a tubular member positioned inside the main body, anda quantity of Thorium-containing molten salt within the main body;generating a proton beam having an average energy level of at least 2.4MeV; directing the proton beam through the lid of the molten saltassembly into the molten salt within the main body to induce (p, n)reactions between protons forming the proton beam and at least onematerial within the molten salt, wherein the induced (p, n) reactionsresult in the production of at least some neutrons having an energylevel of at least 0.7 MeV and wherein: at least some of the producedneutrons interact with Thorium-232 atoms within the molten salt toproduce Thorium-233 atoms; at least some of the produced neutronsinteract with Uranium-233 atoms within the molten salt to fission theUranium-233 atoms; and the fissioning of the Uranium-233 atoms producesheat.

Additionally, or alternatively, methods in accordance with the presentdisclosure may comprising the step of providing a molten salt within theassembly that includes a lithium salt, and/or a Beryllium salt and/orvarying the shape of the proton beam.

Other potential aspects, variants and examples of the disclosedtechnology will be apparent from a review of the disclosure containedherein.

None of these brief summaries of the inventions is intended to limit orotherwise affect the scope of the appended claims, and nothing stated inthis Brief Summary of the Invention is intended as a definition of aclaim term or phrase or as a disavowal or disclaimer of claim scope.

DESCRIPTION OF THE VIEWS OF THE DRAWINGS

The following figures form part of the present specification and areincluded to demonstrate further certain aspects of the presentinvention. The invention may be better understood by reference to one ormore of these figures in combination with the detailed description ofspecific embodiments presented herein.

While the inventions disclosed herein are susceptible to variousmodifications and alternative forms, only a few specific embodimentshave been shown by way of example in the drawings and are described indetail below. The figures and detailed descriptions of these specificembodiments are not intended to limit the breadth or scope of theinventive concepts or the appended claims in any manner. Rather, thefigures and detailed written descriptions are provided to illustrate theinventive concepts to a person of ordinary skill in the art and toenable such person to make and use the inventive concepts.

FIGS. 1A and 1B illustrates an embodiment of an exemplaryaccelerator-driven sub-critical Thorium molten salt system 1000 forgenerating useful energy (for example in the form of process heat and/orelectricity) in accordance with certain teachings of this

FIG. 2A provides details of the exemplary particle beam source 200 ofFIG. 1. disclosure.

FIG. 2B illustrates an exemplary vacuum accelerator assembly 204 thatmay be used to form the particle beam source 200 of FIG. 2A.

FIG. 2C generally illustrates the way the exemplary particle beam source200 may be operated to generate protons of a first energy level.

FIG. 2D illustrates the way the particle beam source 200 of FIG. 2A maybe operated to produce a proton beam of a second energy level, where thesecond energy level is less than the first energy level discussed above.

FIGS. 2E1, 2E2, 2E3 and 2E4 illustrate exemplary first, second, thirdand fourth beam shape and directional combinations that may be generatedusing the exemplary electromagnetic forming and steering assembly 208 ofFIGS. 2A-2D.

FIGS. 3A-3H2 and 3J1-3J3 illustrate aspects of exemplary Thorium moltensalt assemblies 300 that may be used in connection with the exemplarysystem 1000 of FIG. 1.

FIGS. 4A-4H3 and 4J1-4J2 illustrate examples of a novel Thorium fuel rodstructure and fuel rod assembly utilizing such fuel rods constructed inaccordance with certain teachings of this disclosure.

FIG. 5 illustrates an exemplary shielding assembly 700 for use with theexemplary systems 1000 disclosed herein to shield the externalenvironment from particles and rays potentially generated throughoperation of the disclosed exemplary systems.

FIG. 6 provides a very crude, approximated, generalized relativeindication of the amounts of Thorium-232 and Uranium-233 that can existfor the system of FIGS. 1A and 1B over time if it is assumed that theneutron source provides a relatively constant supply of neutrons.

FIGS. 7A-7D provide JANIS-generated graph reflecting the cross-sectionsof various isotopes that may exist within the molten salt assembly 300of FIGS. 1A-1B.

FIGS. 8A-8H generally illustrate how the particle beam source 200 ofFIGS. 1A and 1B may be used to generate particles, such as protons,having first or second energy levels and the direction of thoseparticles to various locations within the molten salt assembly 300 ofFIGS. 1A and 1B.

FIG. 9A illustrates one exemplary method of operating a system 1000constructed in accordance with the teachings of the present disclosureto initially promote the generation of fast neutrons and fission ofThorium (Thorium-232) and thereafter to promote the generation ofthermal neutrons and the fission of Uranium (Uranium-233).

FIG. 9B illustrates a method by which the exemplary system 1000described above may be operated to reduce the amount of undesirablewaste in the system through a burn-down process.

FIG. 9C illustrates a method by which the exemplary system 1000disclosed herein can be operated during the periods of high energydemand to maximize production of energy though fission of Uranium-233and, during periods of low energy demand, operated to promote thegeneration of fast neutrons to burn-up of undesirable waste in thesystem.

FIG. 10 illustrates an alternate embodiment of the system 1000 of FIGS.1A and 1B in which fast and/or thermal neutrons desired for operation ofthe system are generated outside of the molten salt assembly 300.

FIGS. 11A-11F illustrates exemplary neutron source targets 230 that maybe used in connection with the embodiment of FIG. 10.

FIG. 12 generally illustrates the generated neutron flux levels andenergy levels when neutron generating targets such as those illustratedin FIG. 11D are used and a Beryllium target is bombarded with protonshaving energy levels of at least approximately 4.5 MeV and a Lithiumtarget is bombarded with protons having energy levels of at leastapproximately 3.0 MeV.

DETAILED DESCRIPTION

FIGS. 1A and 1B illustrate, in block and rough schematic form a firstembodiment of an exemplary accelerator-driven sub-critical Thoriummolten salt system 1000 for generating useful energy (for example in theform of process heat and/or electricity) in accordance with certainteachings of this disclosure.

As reflected in FIG. 1A-1B, the exemplary system 1000 includes aparticle beam source 200 for producing a particle beam.

In the example of FIG. 1A-1B, the particle beam source 200 is adapted tovary the energy level of the produced particle beam such that the energyof the particles comprising the proton beam can vary between at least afirst energy level and a second energy level, where the first energylevel is at least approximately 4.5 MeV (and potentially up to or above6 MeV) and the second energy level is at least 2.4 MeV.

As reflected in FIG. 1A the particle beam source 200 includes a powerinput 201 for receiving the power required to drive the particle source.

FIG. 2A provides details of the exemplary particle beam source 200 ofFIG. 1. As reflected in FIG. 2, the exemplary particle beam source 200includes a particle generator 202 for generating charged particles. Inthe example, of FIG. 2, the charged particles may take the form of anegatively charged hydrogen nucleus (for example, a neutral hydrogenatom with an added electron). The use of a neutral hydrogen atom with anadded electron is exemplary for purposes of the present discussion andother charged particles may be used without departing from the teachingsof the present disclosure. It should also be noted that the use ofnegatively charged particles is exemplary as well. One could implementthe teachings of the present disclosure using positively-chargedparticles, although the references to positive and negative voltages inthe discussion relating to how the particles are accelerated should beconsidered reversed when dealing with positively-charged particles(i.e., references to negative voltage should be replaced with positivevoltage and vice versa).

In the example of FIG. 2A, the negatively charged generated particlesfrom the particle generator 202 are applied to a vacuum acceleratorassembly 204 that includes several individual vacuum voltage chambers.The vacuum accelerator assembly 204 receives the negatively chargedparticles from the particle generator 202 and accelerates the generatedparticles to provide a high energy particle beam at its output. The highenergy output beam from the vacuum accelerator assembly 204 is providedto an electromagnetic forming and steering assembly 208 that convertsthe received particle beam into an output particle beam having desiredshape and directional characteristics.

FIG. 2B illustrates an exemplary vacuum accelerator assembly 204 thatmay be used to form the particle beam source 200 of FIG. 2A. In theexample of FIG. 2B, the vacuum accelerator assembly 204 is formed fromten individual vacuum voltage chambers 206 a-206 j. Each of the vacuumvoltage chambers is coupled to a vacuum source and to a source ofelectrical power such that the voltage chamber can be evacuated toprovide a vacuum interior and such that a relatively uniform electricalpotential (voltage) level within the chamber can be established. Thevacuum voltage chambers may be arranged in four groups, a first groupcomprising chambers 206 a-206 b, a second group comprising chambers 206c-206 d a third group comprising chambers 206 g-206 h and a fourth groupcomprising chambers 206 i and 206 j. Chambers 206 e-206 f maycollectively be used to form a nitrogen stripping chamber as discussedin more detail below.

FIG. 2C generally illustrates the way the exemplary particle beam source200 may be operated to generate particles having a first energy level.Referring to the figure, in this mode, during operation of the assembly204, the first and second groups of vacuum voltage chambers (i.e., eachof the voltage chambers 206 a-206 d) is energized such that the voltagepotential in these chambers is positive, with the magnitude of theelectrical potential increasing from chamber 206 a to 206 d. Because theparticles generated by the particle generator 202 will have a negativecharge, the positive voltage potential within chambers 206 a-206 d, andthe differential in the magnitude of the positive voltage betweenchambers 206 a-206 d will cause the generate particles to move into andaccelerate through chamber 206 a towards chamber 206 b, with theparticles accelerating as they move through the identified chambers asthe result of the increasing voltage potential from chamber 206 a to 206b. The particles will move into chamber 206 b and be accelerated, in thesame manner, towards and into chamber 206 c. The process will berepeated with the particles continuing to accelerate, and gain energy,as they pass into and through chamber 206 d.

In the illustrated example of FIG. 2C, during this first mode ofoperation, vacuum voltage chambers 206 e and 206 f are configured suchthat they have no net voltage potential. As a result, the particlemoving through these chambers will not be accelerated but will—inessence—“coast” through the chambers 206 e and 206 f as a result of themomentum created by the movement and acceleration provided by chambers206 a-206 d. In the illustrated example, chambers 206 e and 206 f, whilenot maintained at a specific voltage level, are filled with chargednitrogen gas to form a nitrogen stripping chamber. This gas will tend tostrip off electrons from the particles traveling through chambers 206 eand 206 f, thus causing the moving particles to transition fromnegatively charged particles to particles having a positive charge. Inthe specific example under discussion, the stripping chamber will stripoff the two electrons associated with the negatively charged hydrogengenerated by particle accelerator to provide a positively chargedparticle consisting of a single proton.

In the illustrated example of FIG. 2C, in the operating mode, the vacuumvoltage chambers in the third and fourth groups (i.e., chambers 206g-206 j) are activated such that the voltage levels within the chambersare negative, with the magnitude of the voltage levels within thechambers increasing from chamber 206 g-206 j. As a result of theseestablished voltage levels, the positively charged particles travelingthrough chamber 206 f will be attracted into chamber 206 g andaccelerated through chamber 206 g to chamber 206 h where they will befurther attracted toward, and accelerated through, chambers 206 i and206 j. Because of the increasingly negative voltages created withinchambers 206 g-206 j, the particles passing through the chamber willcontinue to accelerate as they pass through the identified chambers toand from a high energy particle beam at the exit of vacuum acceleratorassembly 204.

In the example of FIG. 2B, the voltage levels of the chambers 206 a-206j are established such that the energy level of the particles exitingthe particle beam source 200 are at least on the order of approximately4.5 MeV.

FIG. 2D illustrates a second mode of operating the particle beam source200 of FIG. 2A may be operated to produce a proton beam of a secondenergy level, where the second energy level is less than the firstenergy level discussed above.

The operation reflected by FIG. 2C is like that discussed above withrespect to FIG. 2B except that, in the example of FIG. 2C, only thevacuum voltage chambers in the first and third groups are activated suchthat no voltage potential is established within chambers 206 b, 206 d,206 h or 206 j. As such, the protons traveling through the illustratedassembly will not be accelerated through those chambers and the energylevel of the traveling protons will not increase as they pass throughthe chamber. As a result, the energy level of the protons emitted by theparticle beam source 200 will be at a reduced energy level which, in theexample of FIG. 2C is an energy level of at least about approximately2.5 MeV and below the first energy level.

While a specific exemplary proton generator was described with respectto FIGS. 2A-2D, it should be accepted that other particle beam sourcesmay be used in the exemplary system 1000 of FIG. 1 without departingfrom the teachings of this disclosure. Additionally, while the exemplaryparticle beam source of FIG. 2A was illustrated and described as using avacuum accelerator assembly having only ten voltage chambers, it shouldbe understood that particle beam sources having fewer or more chambersmay be used to carry out the teachings of this disclosure. Stillfurther, while the above example describes operation of a particle beamgenerator to generate beams comprising particles having either a firstor a second energy level it will be appreciated that the teachings ofthis disclosure can be used to provide a particle beam source where theparticles comprising the provided beam can have multiple energy levelsin excess of the two discussed herein and/or where the energy levels ofthe particles comprising the provided beam are well above the firstenergy level discussed herein, and/or below the second discussed energylevel. For example, embodiments are envisioned wherein the first energylevel exceeds about 10 MeV.

Referring to FIG. 2A, the particle beam generated by the vacuumaccelerator assembly 204 is provided to an electromagnetic forming andsteering assembly 208 that transforms the received particle beam into anoutput beam having desired projection pattern (i.e., a desired shape)and directional characteristics. In the example of FIG. 2A, theelectromagnetic forming and steering assembly 208 may take the form of abeam focusing/defocusing instrument. Such an instrument may, in someembodiments, take the form of a quadrupole magnetic assembly that may beenergized to provide output beams having at least first and secondshaped characteristics and multiple directional characteristics.

FIGS. 2E1, 2E2, 2E3 and 2E4 illustrate exemplary first, second, third,and fourth beam shapes that may be generated using the exemplaryelectromagnetic forming and steering assembly 208 of FIGS. 2A-2D

As reflected in FIG. 2E1, the beam provided as an output of the formingand steering assembly 208 may take the form of a focused “spot” beam ora beam having a relatively small primary point of focus. Through properenergization of the beam forming and steering assembly 208, the spotbeam may be directed to a single point, to various points at differenttimes or, in some embodiments, to scan across a general area.

As reflected in FIG. 2E2, the forming and steering assembly 208 canadjust the overall size of the spot beam such that the general diameterof the beam can be greater than the diameter of the narrower spot beamreflected in FIG. 2E1. In addition to providing spot beams of first andsecond diameters, as reflected in FIG. 2E2, the forming and steeringassembly 208 can also be used to provide a spot beam that varies,smoothly or in steps, from a first, relatively narrow spot, to a second,larger-diameter spot.

FIGS. 2E3 and 2E4 reflect operation of the forming and steering assembly208 in an alternate matter to generate a beam that takes the generalform of a ring, with FIG. 2E3 illustrating a ring having a first innerand first outer diameter, and FIG. 2E4 illustrating a ring having asecond inner and second outer diameter, where the second inner diameteris greater than the first inner diameter and where the second outerdiameter is greater than the first.

Although not illustrated in FIGS. 2E1-2E4, embodiments are envisionedwhere rings of various inner and outer diameters can be produced byassembly 208 and/or where rings of variable sizes may be generated suchthat the beam can be varied from a spot to rings of increasing inner andouter diameters until a maximum outer diameter is reached, down again toa spot through rings of progressively decreasing inner/outer diameters,and then have the process repeated again in a cyclic fashion. Thisvariation can be accomplished by smoothly changing beam shapes orthrough steps. During such cyclic operation, the amount of time thesystem is maintained at the various shape and directional points can bevaried such that the system, for example, dwells at a spot point for afirst period of time, and then cycles through rings of various sizes fora second period of time, where the first period of time is longerthan—and potentially multiples of—the second period of time.

In addition to providing particle beams of varying shapes and varyinggeneral energy levels, the particle beam source 200 of the presentexample can be controlled to provide particle beams of varying intensity(or current). This can be accomplished by controlling the operation ofthe particle generator 202 to generate fewer or more particles at anygiven time.

Referring to FIGS. 1A and 1B, in the exemplary system, the particle beamgenerated by the particle beam source 200 is provided to a Thoriummolten salt assembly 300.

FIGS. 3A-3H2 and 3J1-3J3 illustrate aspects of exemplary Thorium moltensalt assemblies 300 that may be used in connection with the exemplarysystem 1000 of FIG. 1.

Turning first to FIGS. 3A-3D, a first exemplary Thorium molten saltassembly 300 is illustrated. As reflected in the figure, the illustratedThorium molten salt assembly 300 includes a main body 302 in the form ofa large, tub-like structure. The main body 302 forms a vessel which maycontain molten salt including Thorium. In general, the main body 302should be formed from a substance that can withstand the environmentthat will exist within and outside of the assembly 300. In particular,the main body 302 should be formed from a material that is generallyresistant to the chemical characteristics of the molten salt fluid thatwill be contained within the assembly 300. While a variety of differentmaterials may be suitably utilized, nickel-based steel alloys, such asHastelloy-N, may be used to form the main body 302 and, indeed, allcomponents in contact with molten salts comprising the various exemplarymolten salt assemblies discussed herein. Other potentially suitablematerials include stainless steels or Incolloy. Additionally, coatingscan optionally be applied to the identified (and other) materials toenhance their resistance to corrosion.

As reflected in FIGS. 3A-3D the bottom of the main body 302 is generallyrounded. This rounded bottom shape is believed to be beneficial inpromoting optional fluid circulation within the assembly 300. The roundbottom can also be of benefit in properly locating the assembly 300within a shielding structure, as discussed in more detail below.

In the example of FIGS. 3A-3D the main body 302 is coupled by, forexample welding to a lower flange element 304. The lower flange element304 defines a lower flange surface that, in turn, defines a plurality ofbolt openings (unlabeled in FIGS. 3A-3B).

An upper lid assembly 306 is coupled to the lower flange element 304.The outer portions of the upper lid assembly 306 define an upper flangesection (not separately labeled) that is arranged in general alignmentwith the lower flange element 304. The upper flange section of the lidassembly 306 defines a plurality of bolt holes where the bolt holes arepreferably of the same number and sized to align with the bolt openingsof the lower flange element 304.

While the number of bolt openings can vary, in preferred embodiments atleast eight bolt openings are provided. In the example of FIGS. 3A-3Bboth the lower flange element 304 and the upper flange section of lid306 defines sixteen bolt openings. Bolts 308 (only one of which islabeled in FIGS. 3A-3D are used to couple the lid 306 to the lowerflange element 304. The use of bolts to couple the lid 306 to the lowerflange element 304 is exemplary and other forms of coupling may be used.For example, screws, clamps and other mechanical assemblies may be use.In embodiments where ready separation of the lid assembly from the lowerflange element 304 is undesirable, welding may be used. The use of boltsin FIGS. 3A-3D permits ready attachment and separation of the lowerflange element 304 and the upper flange section of lid 306, simplifyingthe assembly and disassembly of the exemplary molten salt assembly 300.

As illustrated in FIGS. 3A-3D, the bolt openings in the lid assembly 306and the lower flange element 304 are such that they open outside theinterior of the main body 302 in which the molten salt will be located.As such, the bolt openings do not give rise to any penetrations into theinterior of the main body 302.

Referring to FIG. 3D, which shows a top-view of the lid assembly 306, itmay be seen that in the illustrated exemplary embodiment (in addition todefining bolt openings 310, only four of which are labeled in FIG. 3D)the lid assembly defines four impeller openings 312 a-312 d that passfrom the outside of the lid assembly 306 into the interior of the mainbody. The lid 306 further defines two heat exchanger openings 314 a and314 b that provide openings that extend from the exterior of the mainbody 302 into the interior of the main body 302.

As best reflected in FIG. 3D, the lid 306 is a two-piece assembly thatincludes a generally ring-shaped main section of a first thickness andan inner disc-element 316 of a second thickness, where the secondthickness is less than the first thickness. The window element 316 isintended to provide a “window” into the interior of the main body 302through which certain types of particles, specifically at least theparticles provided by the particle beam source 200 (and, potentially,neutrons) can pass. In the example of FIGS. 3A-3D, the window 316 isformed from a disk of any suitable material and may take the form oftitanium, or aluminum titanium, or any other suitable material that willpass the particles provided by the particle beam source 200. The windowelement 316 should have a thickness sufficient to pass particle beams ofthe type necessary for operation of the systems described in thisdisclosure.

The window element 316 maybe coupled to the ring-shaped section of lid306 in any suitable manner. In some embodiments, the window element maybe bolted onto, screwed onto, screwed into or otherwise mechanicallycoupled to the ring-shaped section of lid 306. In other embodiments, thewindow element 316 may be welded to, brazed to, integrally formed withinor otherwise attached to the ring-shaped section.

While the window element 316 is illustrated as being circular in shapein FIG. 3D, it should be understood that the window element 316 may takethe form of other shapes such as, for example, a square, oval, orpentagon. In still other alternative embodiments, instead of a singlelarge window element 316, multiple window elements are provided wherethe collection of window elements collectively define multiple passagesthrough which high energy protons can enter the main body 302.

As best shown in FIGS. 3A-3C, in the example under discussion, aplurality of motor-driven impeller pumps 318 a-318 d are provided. Thegeneral construction of each of the impeller pumps is shown in FIGS.3E1-3E2.

As reflected in FIGS. 3E1-3E2, in the exemplary embodiment underdiscussion, each of the impeller pumps 318 includes a variable speedmotor 320 that is coupled to a shaft 330. The variable speed motor maytake the form of any suitable variable speed motor such as a variablefrequency induction motor, a brushless permanent magnetic motor or aswitched reluctance motor. In the example of FIGS. 3E1-3E3, the variablespeed motor 320 takes the form of a variable frequency driven inductionmotor. Although not illustrated, it will be understood that such a motorwill include a rotor and a stator with windings and the windings will becoupled to a variable frequency drive that can provide power to themotor 320 in such a manner that the rotational speed of the motor can becontrolled.

As shown in FIG. 3E3, the motor shaft 330 extends downward from themotor and is coupled to an impeller element 332.

In the example under discussion, the pump further includes a bearingassembly 322 through which the shaft 330 passes. As described in moredetail below, the bearing assembly 322 of each impeller pump 318 in theexample under discussion is positioned within one of the impelleropenings of the lid 306. Because the impeller shaft has to pass throughthe top lid, the penetration should include high temperature seals toprevent the leakage of materials and gases from the interior of the mainbody 302 to the exterior of the body.

The illustrated impeller pump 318 also include a pump body 324 thatdefines an upper fluid opening 326 and a lower fluid opening 328.

The impeller pump 318 is designed such that, during operation,activation of the motor 320 will result in rotation of the shaft 330and, therefore, rotation of the impeller element 332. The rotation ofimpeller element 330 will create a pressure differential across theinner chamber defined by the pump body 324 such that fluid will tend tobe drawn into the upper fluid opening 326, flow through the chamberdefined by pump body 324, and out the lower fluid opening 328. Therotational speed of the motor can be controlled to vary the pressuredrop through the pump body 324 and, thus, the extent of the fluid flowthrough the pump.

Referring to FIG. 3C it may be seen that the molten salt assembly 300also includes a tubular member 340 positioned within the main body 302.The tubular member 340 includes openings at both its top and bottom endssuch that liquid, such as a Thorium-containing molten salt, can flowinto the bottom of the tubular member 340, up through the tubularmember, and out, over the top of the tubular member 340. As bestreflected in FIG. 3C, the bottom of the tubular member 340 can define alower ledge structure.

In general, the tubular member 340 defines an interior space within themain body 302 within which, and among, various structures can bepositioned and through which liquid can flow.

Referring to FIGS. 3B, 3C and 3F, it may be seen that the tubular member340 and the impeller pumps 318 are dimensioned such that the upper fluidopening 326 opening of the pump body 324 includes a portion that extendsbelow the top of the tubular member 340 and the lower fluid opening 328of the tubular member 340 is positioned above the bottom of the tubularmember 340. As reflected in the figures, the length of the tubularmember 340 and the impeller pump 318 are such that the bottom end of thetubular member and the lower fluid opening 328 of the impeller pumps 318are within the lower portion of the main body 302 such that an adequateflow path (to the left in the figure) is provided. In the specificexample in the referenced figures, the lower fluid openings of theimpeller pumps are within the lower one-third of the main body 302. Theresult of such positioning is that operation of the impeller pumps 318will tend to cause fluid to flow up and out of the tubular member 340,over the top of the tubular member 340 and down through the main body302 (and partially through the pump body 324). Thus, operation of theimpeller pumps 318 a-318 d will tend to cause fluid flow within the mainbody 302 along the path generally reflected by the arrows in FIG. 3F.

As will be appreciated, the fluid flow path depicted in FIG. 3F willexist for each of the four impeller pumps 318 a-318 d illustrated inFIGS. 3A-3F. As such, operation of the impeller pumps will tend toresult in a circulating flow of fluid where fluid flows through acirculation path whereby it initially circulates into the bottom of thetubular member 340, flows up through the tubular member 340, then outand over the top of the tubular member 340, and down the outside of thetubular member 340, where it circulates back up and into the bottom ofthe tubular member and the cycle is repeated.

In the embodiment of the molten salt assembly 300 previously described,and in all embodiments of the assembly 300 discussed herein a Thoriumcontaining molten salt will be held in the main body 302. While theexact composition of the molten salt within the main body 302 will vary,embodiments are envisioned where the molten salt will contain at least aLithium salt, a Beryllium salt and a Thorium salt, such that Lithium,Beryllium and Thorium exist within the molten salt. One suitable salt isa FLiBe salt containing dissolved Thorium. Other embodiments areenvisioned wherein the molten salt does not include Beryllium but doesinclude Lithium. One such salt is FLiNaK. In general, the quantity ofmolten salt within the main body 302 should be such that the upper levelof the molten salt is over the top of the tubular member 340. Stillfurther embodiments are possible where the molten salt is a chloridesalt that contains chlorine, as opposed to fluorine.

FIGS. 3G1 illustrates a cross-section of the main body 302 and includesa dashed line 342 reflecting the general level of molten salt in theexemplary assembly 300. As reflected in FIG. 3G1, the upper level of themolten salt is both above the upper surface of the tubular member 340and below the lower surface of the lid assembly 306. As such, an openregion 346, not including any molten salt, but capable of containinggases, exists between the level of the molten salt and the lower surfaceof the lid 306 (and the lower surface of window element 317 for theinterior region of the illustrated assembly). This open region 346 isfurther illustrated by the dark gray areas of FIG. 3G2. This open region346 may be used to store gases generated as a result of fissionprocesses that can occur within the main body 302. In certainembodiments, the open region 346 can initially be filled with an inertgas, such as argon, prior to the operation of the system.

In the embodiment of FIGS. 3A-3F, impeller pumps 318 a-318 d are used tocirculate the fluid in the main body 302. Alternate embodiments areenvisioned wherein natural circulation is used to provide a fluid flow,generally along the path described above with respect to FIG. 3F. Suchan alternate embodiment is depicted in FIGS. 3J1, 3J2 and 3J3.

Referring to FIGS. 3J1 and 3J2, it may be noted that the overallstructure of the illustrated exemplary molten salt assembly 300′ is likethat described above in connection with FIGS. 3A-3F, with the primarydifferences being that the main body 302′ of the embodiment of FIGS. 3J1and 3J2 is taller and narrower than the main body 302 of thefirst-described embodiment, the tubular member 340′ is longer andnarrower than the tubular member 340 in the first-described embodimentand the helical heat exchanger assembly 500 (discussed in more detail)below is positioned about the upper two-thirds of the tubular member340′ and not about the lower one-third of the tubular member 340′. Ingeneral, this arrangement creates a situation whereby the removal ofheat through use of the helical heat exchanger assembly 500 createsconditions where natural circulation causes the fluid within the mainbody to flow along the paths identified by the arrows in FIG. 3G2.

Advantages of the embodiment reflected in FIGS. 3J1-3J2, includesimplification of the design and construction of the assembly 1000through the elimination of the impeller pumps and the need for equipmentto control the pumps; elimination of the need for impeller openings inthe lid coupled to the main body 302′, thus reducing the number ofpenetrations that must be made into the main body, and elimination ofthe need to provide energy for operation of the motors driving theimpeller pumps. The minimal penetrations required for implementation ofthis embodiment is reflected in FIG. 3J3, where only two penetrations314 a′ and 314 b′ into the main body are provided, one for the inflow ofa heat exchange fluid for the outflow of heat exchange fluid.

In certain embodiments of the molten salt assemblies 300 describedpreviously one or more solid Thorium fuel rods will be positioned andlocated within the interior of the tubular member 340 (or 340′).References herein to a solid Thorium fuel rod are intended to indicatethat the fuel rod contains solid Thorium (as opposed to Thoriumdissolved in a molten salt). As such, a solid Thorium fuel rod, as thatterm is used herein, may define internal openings or chambers.

In embodiments as described above, Thorium fuel will be available withinthe interior of the tubular member 340 (or 340′) both in the form ofsolid Thorium within the Thorium fuel rod, but also in the form ofdissolved Thorium within the molten salt. FIGS. 4A-4E illustrate oneexample of a novel Thorium fuel rod 400 constructed in accordance withcertain teachings of this disclosure.

Referring to FIGS. 4A-4E a Thorium fuel rod 400, is illustrated thatincludes an interior Beryllium core element 402 and an outer, solidThorium-containing fuel element 404. In the illustrated example, theThorium containing fuel element 404 is formed from a solidThorium-containing material, such as metallic Thorium. Alternativeembodiments are envisioned where the element 404 is formed from aThorium-containing solid material (such as Thorium Dioxide) and an outercladding

In the example of FIG. 4A-4E, the outer surface of the Thorium fuelelement 404 defines a series of fins that may be twisted to form agenerally spiral-like outer structure. Alternative embodiments areenvisioned wherein the fins on the Thorium fuel element are straight orgenerally straight.

In the example of FIGS. 4A-4E, the Beryllium core element 402 is formedfrom a generally tubular element of Beryllium-containing material, suchas metallic Beryllium. The generally tubular element is formed from astructure that defines an interior cavity 408 that, at any givencross-sectional point, defines an open cross section roughly in the formof a four-leaf clover surrounding a central circular opening. In theillustrated example, the Beryllium core element 402 has a length that isgreater than the length of the solid Thorium fuel element 404 such thatthe Beryllium core element 402 extends out from the top of the Thoriumfuel element.

In one embodiment, the length of the Beryllium core element 402 is suchthat the solid Thorium fuel element 404 can be completely submergedwithin the molten salt while the top of the Beryllium core element isabove the level of the molten salt. In general, the length of theBeryllium core element 402 extends along a majority of the length of thesolid Thorium element 404, and preferably along at least 75% of thelength of the solid fuel element 404. Embodiments are envisioned whereinthe Beryllium core element 404 extends along 100% of the length of thesolid fuel element 404.

The cross-section of the Beryllium core element 402 at a given exemplarypoint is roughly reflected in FIG. 4E. As reflected in FIG. 4E, at anygiven point along the Beryllium core element 402, four solid Berylliumprojections (410 a, 410 b, 410 c and 410 d) project into the interior ofthe core and define four lobe-shaped openings 412 a, 412 b, 412 c and412 d and a generally circular central opening 414.

The construction of the Beryllium core element 402 is such that, fromthe top of the element 402 to the bottom, the relative position of thesolid Beryllium projections 412 a, 412 b, 412 c and 412 d change suchthat they form a general spiral down the interior of the core element402. The result of such a construction is that they define a centralcavity 408 having a circular cross-section that extends from the top ofthe core element 402 to approximately the bottom of the element 402 andgenerally clover-leaf openings 412 a-412 d that have the characteristicsdescribed below. In the illustrated example, the clover-leaf openingsare such that, for any particular cross-section, there is at least aportion of at least one of four of the solid projections from a lowercross section that extend into the openings. This means that particlespassing through the openings 408 a-408 d at any given cross-sectionalpoint will always have at least some solid Beryllium beneath theopenings upon which the particles may impinge. In general, the specificpitch of the spiral and the size of the projections and lobe-shapedopenings will depend on the amount of power to be generated, the energyof the incident protons, and other factors.

As reflected in FIGS. 4A-4D, the length of the Beryllium core element402 is greater than the length of the Thorium fuel element 404 such thatthe core element 402 extends from the top of the solid Thorium fuelelement 404.

In at least one embodiment of the present example, the exemplaryembodiment of FIG. 4A-4E the interior void space within the Berylliumcore will be subjected to a vacuum and the void space of the Berylliumcore sealed to maintain a vacuum. The sealing can be done through anysuitable end cap provided that the end cap is formed of a materialthrough which the particles provided by the particle beam source 200 canpass. Alternate embodiments are envisioned wherein the top ends of eachBeryllium inner core are left open and all the ends are coupled to amanifold assembly that is attached to a vacuum pump to maintain a vacuumwithin the interior void space of the Beryllium core.

In general, each of the Thorium fuel rods 400 is capable of generatingpower through fission reaction that can be caused to occur by directinga beam of energetic particles, such as protons with an energy level onthe order of above 4.2 MeV into the interior of the Beryllium core.Particles in such a beam may pass into the void space of the Berylliumcore and travel until they contact a Beryllium nucleus on one of thesurfaces extending into the core. The collision of the high-energyparticle (in one exemplary embodiment a proton) with the Berylliumnucleus can result in a (p, n) reaction that produces a neutron havingan incident energy level on the order of 1 MeV or greater. One or moreof such generated “fast” neutrons can strike a Thorium nucleus withinthe Thorium element 404 and cause a fission reaction in which theThorium nucleus undergoes nuclear fission and releases a significantamount of energy.

Depending on the desired operating characteristics of the assembly 1000one or more of the Thorium fuel rods 400 may be positioned within thetubular member 340. In certain embodiments, the Thorium fuel rods to bepositioned within the tubular member 340 are positioned between twosupport elements and the support elements are configured to rest withinthe tubular element 340 in such a manner that the solid Thorium fuelelements 404 in the fuel rods 400 are submerged in the molten salt, andthe top portions of the Beryllium cores 402 within the fuel rods extendabove the level of the molten salt. In these embodiments, the toppositions of the fuel rods 400 are all positioned such they are underthe window element 316 such that particles from the particle beamprovided by particle beam source 200 can pass through the window 316 andinto the various Beryllium core elements.

FIGS. 4F1 and 4F2 illustrate an exemplary embodiment in which a singleThorium fuel rod 400 is positioned within the tubular member 340. In theillustrated example, as in the other examples discussed below, theThorium fuel rod (or rods) 400 are positioned between an upper supportelement 430 and a lower support element 432. FIG. 4F1 illustrates atop-down view, showing where the Thorium control rod 400 is positionedwithin the window element 316. FIG. 4F2 provides a generally isometricview indicating the positioning of the assembly containing the Thoriumfuel rod 400 relative to the lid 406. In the isometric view of FIG.4F2—and the isometric views of the other Thorium rod structuresdiscussed in more detail below, the portion of the Beryllium coreelement 402 that extends out of and above the solid Thorium fuel element404 is not illustrated but should be understood to be present.

FIGS. 4G1 and 4G2, 4H1, 4H2 and 4H3 illustrate alternate fuelarrangements that include either five Thorium fuel rods (FIGS. 4G1 and4G2), thirteen Thorium fuel rods (FIG. 4H1 and 4H2) or seventeen Thoriumfuel rods (FIG. 4H3). As reflected in FIGS. 4G1, 4G2, 4H1 and 4H2, incertain illustrated embodiments the Thorium fuel rods to be used in thesystem are combined in a single solid Modular Thorium fuel package thatincludes the solid Thorium fuel rods (or rod) positioned between twosupport elements. The use of such a solid Modular Thorium fuel packagecan permit efficient refurbishing of the system 1000 described hereinfor subsequent operations. In addition, the use of a Modular Thoriumfuel package as disclosed herein also permits the construction ofsystems of different power levels through the use of one fuel package inplace of another.

As briefly discussed in the previously illustrated embodiments, theBeryllium core elements are used to provide solid targets upon whichhigh energy protons can impinge to generate high energy (for exampleover 0.7 MeV) neutrons that can strike Thorium to induce a fissionreaction within the Thorium nucleus, generating additional high energyneutrons and energy. FIGS. 4G1 and 4G2 illustrate an alternative solidModular Thorium fuel package in which a different approach is used togenerate high energy neutrons for the fast fission of Thorium.

Referring to FIGS. 4J1 and 4J2, a solid Thorium fuel assembly isillustrated that includes four solid Thorium rods (FIGS. 460a-460d )surrounding a single, central solid Beryllium rod 462. In theillustrated embodiment, the central solid Beryllium rod 462 is used as atarget in which the high energy particle beam from the particle beamsource 200 is projected. When such high energy particles strike theBeryllium rod 462, high energy (fast) neutrons can be generated whichcan exit the Beryllium rod and impact upon Thorium in the solid Thoriumrods (460 a-460 d) to cause fast Thorium fission reaction.

In the embodiments of FIGS. 4J1 and 4J2 the central Beryllium rod 462 issolid. As such, the particles impinging on the rod from the particlebeam source 200 may not penetrate the lower portions of the Berylliumrod 462. To promote such penetration and utilization of the entirety ofthe Beryllium rod to generate fast neutrons, a Beryllium rod in thegeneral form of the one described above in connection with FIGS. 4D and4E may be substituted for the solid rod 462. In the embodimentsdiscussed above in connection with FIGS. 4A-4H3 and 4J1-4J2 theBeryllium within the Beryllium rods may be in the form of solidBeryllium. Alternative embodiments are envisioned wherein the Berylliumwithin the Beryllium rods takes alternative forms, such as aBeryllium-containing salt (e.g., FLiBe). In such embodiments, theBeryllium-containing rods would comprise a vessel capable of containinga molten Beryllium-containing salt.

Referring to FIGS. 1A and 1B and 3H1 and 3H2 a primary heat exchangeassembly 500 is shown as extending around the central tubular member312. The illustrated exemplary primary heat exchanger includes an inputpipe 502 and an output pipe 504. The input pipe 502 is coupled to aninput manifold 506 (illustrated in FIGS. 3H1-3H2) and the output pipe504 is coupled to an output manifold 508. Notably, the lengths of theinput and output pipes are sufficiently long so as to pass through thetop level of the Thorium-containing molten salt, into the gaseous headmaintained above the molten salt and potentially through the top lid ofthe main body.

As reflected in the exemplary figures, a plurality of helically formedcoiled pipes 510, ten in the illustrated example, have one end coupledto the input manifold 506 and another end coupled to the output manifold508. As reflected in the figures, each of the helical pipes 510 windsdownwardly around and back up the tubular member 12 from the inputmanifold to the output manifold 508. The illustrated number of helicallyformed coiled pipes is exemplary only and a different number of pipescould be used without departing from the teachings of the presentdisclosure. In the embodiment of FIGS. 1A-1B the primary heat exchangeassembly includes a non-Thorium containing molten salt within the pipes510 and input and output manifolds 506 and 508. As described in moredetail below, this non-Thorium containing molten salt is circulatedthrough the primary heat exchanger to remove heat from the Thoriummolten salt assembly 300. Pumps (not illustrated) may be used tocirculate the non-Thorium containing molten salt.

Select details of an exemplary primary heat exchange assembly 500 areshown in FIGS. 3H1 and 3H2. FIG. 3H2 reflects the construction of anexemplary manifold 506. The illustrated manifold construction may beused for both the input manifold and the output manifold. Referring toFIGS. 3H1 in the illustrated example, the manifold includes a box-likemain manifold base 560 that defines a single input (or output) opening562 of a first diameter at the top of the base 560 and a plurality ofoutput (or input) openings 564 of a second diameter at the bottom of thebase, only two of which are labeled in the figure. In this embodiment,the second diameter is less than the first diameter. In the illustratedexample, the input 562 is axially offset from each of the plurality ofopenings 564, such that there is no straight flow path through the firstopening 562 and any of the second openings 564. In the illustratedexample, there are twelve (12) openings 562. Each of the second openingsis coupled to a heat exchange coiled pipe 566.

Use of the exemplary manifold described above permits the use of aplurality of lesser-diameter heat exchange coils (twelve in the example)within the main body 502, while requiring only two penetrations throughthe main body 502.

In the exemplary embodiment discussed herein, heat generated within themain body 502 will be transferred to the molten salt flowing through theprimary heat exchange assembly 500. In the illustrated example, thatheat is transferred from the primary heat assembly 500 to a secondaryheat assembly 512.

Details of the secondary heat exchanger assembly 512 are shown in FIG.1B. As reflected in FIG. 1B a secondary heat exchange path 516 isprovided and arranged to absorb heat from the primary heat exchangecoil. In the example of FIG. 1B, a vapor-forming liquid—such as water orcarbon dioxide—is contained within the secondary heat exchange path (orcoil) 516 and the piping attached to the secondary heat exchanged coil.A condenser 518 is also provided in the illustrated system as is piping(not labeled) that can transport liquid from the condenser 518 to theinput of the secondary heat exchange coil and steam from the output ofthe secondary heat exchange coil to the input of the condenser.

Not illustrated in FIG. 1A or 1B are pumps that can be used to circulatenon-Thorium containing molten salt through the primary heat exchangeloop and vapor-producing liquid (such as water or carbon dioxide)through the secondary heat exchange loop.

In the example of FIG. 1, the energy transfer assembly 500 is used totransfer energy from the Thorium molten salt assembly 300 to a powergenerator assembly 600. High level details of such a system may also befound in FIGS. 1A-1B which reflect the application of the vaporgenerated by the heat exchange tank 512 to a turbine assembly 602 which,in turn, is coupled to an electric generator 604. In accordance with thegeneral operation of turbine-driven electrical generators, the vaporproduced by the energy transfer that occurs within the heat exchangetank 512 is used to drive/turn turbine 602 which turns the rotor of theelectrical generator 604, producing electrical power at the output 606of the electrical generator 604. In the illustrated system the output606 of the electrical generator 604 is provided to a distributionelement which distributes the generated electric power such that themajority of the generated power is provided to a main power output 608and a portion of the generated power is provided to the power input ofthe proton generator 201 to drive the particle beam source 200.

Because the operating of the system 100 of FIGS. 1A and 1B can generatenuclear particles and radiation emission, appropriate shielding 700 isprovided to block the transmission of undesired particles and waves.FIG. 5 illustrates one exemplary way this shielding may be provided. Inthe illustrated example of FIG. 5, many of the components of the system1000 are placed in a containment system 700. In the exemplaryembodiment, the containment system 700 comprises a first containmentstructure 702 in which the particle generator 202 and the vacuumaccelerator assembly 204 are located. Vacuum tubes (unlabeled) arecoupled to the output of the vacuum accelerator assembly 204 and couplethe output of the vacuum accelerator 204 to the forming and steeringassembly 208, which is positioned in second containment structure 704.The molten salt assembly 300 is partially placed within the ground underthe second containment structure 704 such that the lid of the moltensalt assembly is accessible above ground. A third containment structure708 is provided below the molten salt assembly 300. The space 706between the molten salt assembly 300 and the third containment structure708 may be filled with any suitable material, such as soil, boratedmaterial, concrete, or any other suitable material or blend ofmaterials. Depending on the particular application of the system 1000,and the extent to which safety requirements dictate, the containmentunits 702, and 704 may take the form of a simple metallic structure (ifthe earth, rock or ground structure is capable of providing the desiredshielding) or a structure intended to block the transmission ofradiation (e.g., lead-walls or a lead-brick structure). The structure708 should be formed of a material sufficient to contain molten salt inthe possibility that there is damage to the molten salt assembly.Alternate embodiments are envisioned wherein the containment unit 700comprises a structure having an internal dry core area into which thecomponents of system 1000 to be shielded are placed and an externalstructure capable of holding water (or a water/chemical mix (e.g.,borated water) which acts as a shielding material. In any or all thevarious embodiments of the containment unit 700 a surface layer ofshielding material 702 (e.g., a lead blanket) may be used.

In operation, at a very high level, the system illustrated in FIGS. 1Aand 1B operates by powering the particle beam source 200 to generate aproton beam that is applied to the Thorium molten salt assembly 300. Oneor more of the protons within the proton beam may impact upon one ormore of the atoms within the Thorium molten salt assembly 300 to either:(a) produce neutrons or (b) result in a nuclear fission reaction, whichwill generate heat and further neutrons. These generated neutrons may,in turn, impact and interact with other atoms within the Thorium moltensalt assembly 300 to generate additional heat. The generated heat may beremoved through operation of the primary and secondary heat exchangesystems, and the removed energy may be converted to electric energythrough use of the electric generation system 600, described above.

The exemplary system 1000 of FIGS. 1A and 1B may be arranged to permitoperation of the system in one of several alternative operating modes.

In one operating mode, the proton beam provided by the particle beamsource 200 is shaped and aimed such that the proton beam provided by thegenerator is directed through the window element 316 primarily into theThorium containing molten salt within the tubular member 302 without asubstantial number of the protons (or any) impinging upon the Berylliumcores of the Thorium fuel rods 400 positioned within the tubular member340.

In this operating mode, one (or more) of the protons from the protonbeam from generator 200 may impact one (or more) of the atoms within theThorium containing molten salt. For example, one or more of the protonsfrom the proton beam may impact with a Lithium nucleus forming part ofthe molten salt. This interaction of the proton with the Lithium nucleuscan cause a (p, n) reaction under which the Lithium nucleus absorbs theincident proton and emits a neutron. The neutrons emitted by suchproton-Lithium reactions may be of varying energy levels, the greatestnumber of neutrons resulting from several such reactions would be at anenergy level of between 0.1 and 0.7 MeV. As another example, one or moreof the protons from the proton beam may impact with a Beryllium nucleusforming part of the molten salt to cause a (p, n) reaction in which theBeryllium nucleus may absorb the incident proton and produce a neutronat a particular energy level. The neutrons emitted by suchproton-Lithium reactions may be of varying energy levels, the greatestnumber of neutrons resulting from several such reactions would be at anenergy level of between 0.7 MeV and just over 1.0 MeV. Notably, the peakenergy level of the neutrons emitted by the described proton-Beryllium(p, n) reaction will be greater than those emitted as a result of thedescribed proton-Lithium (p, n) reaction.

In a second operating mode, the proton beam provided by the particlebeam source 200 may be shaped and aimed such that all or a substantialportion of the proton beam is directed through the window assembly insuch a manner that a substantial number of the protons forming theproton beam are directed to one or more of the Beryllium cores of theThorium fuel rods within the tubular member 340. This may beaccomplished by forming the proton beam into a generally narrow beamshape and directing the narrow beam to the Beryllium core of the centralThorium fuel rod. This may also be accomplished by forming the protonbeam into a ring and directing the ring such that it covers either thefirst group of Thorium fuel rods or the second group of fuel rods.Alternatively, the beam may be formed such that it transitions from abeam directed to the central Thorium fuel rod, to a first ring directedto the first group of fuel rods to a second ring directed to the secondgroup of fuel rods. In general, forming and aiming the proton beam asdescribed in connection with the second operating mode will tend tocause protons within the proton beam to strike Beryllium, thusgenerating neutrons through the process described above.

In the embodiment of FIGS. 1A and 1B the average energy levels of theprotons within the proton beam generated by the particle beam source 200may be varied, depending on the operating mode of the system to preferproton-Lithium interactions, thus producing neutrons with averageenergies below 0.7 MeV or to prefer proton-Beryllium interactions, thisproducing neutrons with average energies above 0.7 MeV.

For example, when the system is operated in accordance with the firstoperating mode, the energy level of the protons provided by the protongenerator may be set to be on the order of at least approximately 2.4MeV and about 3.0 MeV. The size and form of the proton beam, along withthe energy level of the proton beam and the fact that it is directedinto the Thorium containing molten salt, are such that operation of thesystem in the first operating mode will tend to result in protonproduction of neutrons of an energy level on the order of between 0.1MeV and just over 1.0 MeV with the peak energy level of the producedneutrons being on the order of about 0.7 MeV.

In the same example, using the system described above in connection withFIGS. 2A-2D, when the system is operated in accordance with the secondoperating mode, the particle beam source 200 may be operated to producea beam of protons where the protons forming the beam have energy levelson the order of 4.5 MeV. The size and form of the proton beam, alongwith the energy level of the proton beam and the fact that it isdirected into the Thorium containing molten salt, are such thatoperation of the system in the first operating mode will tend result inproton production of neutrons of an energy level on the order of 0.1MeV-1.2 MeV, with the majority of the produced neutrons having energylevels on the order of between 1.0-1.1 MeV.

The likelihood of the particles from the particle beam 200 interactingwith one or more of the atoms within the main body 302 will varydepending on a large number of factors including, but not limited to:the energy level of the particle provided by the accelerator, theparticular nucleus involved in the potential interaction, and the otheratoms within the body 302. The system 1000 takes advantage of some ofthese variables, and of the different types of reactions that can occurwithin the main body 302 to provide a system that can be operated invarious modes, to provide various output characteristics.

To understand the various modes in which the exemplary system of thepresent disclosure may be operated, it is helpful to understand some ofthe operations that can occur within the body 302.

As briefly discussed above, in the system of FIGS. 1A and 1B, onceneutrons are created within the main body 302 (e.g., by a high energyproton provided by the proton beam colliding with a Lithium nucleus or aBeryllium nucleus within the molten salt or as a result of a fissionreaction occurring within the main body and producing resultantneutrons) some of the neutrons within the main body 302 may collide witha Thorium nucleus in the molten salt solution and cause a nuclearreaction. In the illustrated system, the nuclear reaction caused by thedescribed collision can be one of at least two different types ofreactions. In one type of nuclear reaction, referred to as a “fission”reaction, the nucleus of the involved Thorium atom will split into,typically two, smaller nuclei. Such a fission reaction will release avery large amount of energy and one or more neutrons. The energyreleased by the fission reaction will tend to increase the amount ofenergy stored in the molten salt within assembly 300 as heat. One ormore of the neutrons released by such fission reaction may interact aThorium nucleus within the molten salt fuel to cause further Thoriumfission reactions.

In a second type of nuclear reaction, known as “neutron capture” (or“neutron absorption”) the nucleus of the involved Thorium nucleus willabsorb the involved neutron to form an isotope of Thorium, namelyThorium-233 (²³³TH). Thorium-233 is an unstable isotope that will decayto Protactenium-233. The decay of Thorium-233 to Protactinium occursrelatively quickly as the half-life of Thorium-233 is about 22 minutes.Protactenium-233 is an unstable element that will tend to decay toUranium-233, with the half-life of Protactinium-233 being approximately27 days.

Uranium-233 is fissile material. As such, whenever Uranium-233 existswithin the molten salt and neutrons are available—either from theparticle beam source 200 or from the fission of other atoms within themolten salt—there is the potential that a neutron can strike aUranium-233 nucleus causing a fission reaction. The fission reactionwill produce heat. As with fission of the Thorium nucleus, fission of aUranium-233 will result in the release of substantial energy and severalneutrons, those neutrons may, in turn, interact with a Uranium-233nucleus within the molten salt to produce a secondary Uranium-233fission reaction, with a Thorium-232 nucleus to produce a Thorium-233nucleus, or with other materials within the molten salt assembly 300.Some of the neutrons may pass through and escape the molten saltassembly.

Once started and put into operation, the illustrated embodiment of FIGS.1A and 1B can be self-sustaining in the sense that it can operate toprovide usable energy without the addition of any other external poweror energy as long as the energy generated by the system is sufficient toprovide the power needed to drive and operate the particle beam source200.

Once the embodiment of FIGS. 1A and 1B begins to operate, theconstituent components comprising the molten salt solution will changeover time. At a high level, in certain embodiments, the composition ofthe molten salt will initially include no, or negligible, Protactiniumand no, or negligible, Uranium. For purposes of this disclosure anegligible amount of an element is intended to refer to a substantiallynon-detectable amount of an element that exists in the absence of anyintentional inclusion or addition of the element to the material.Alternate embodiments are envisioned wherein the molten salt couldinitially contain at least some Uranium.

FIG. 6 provides a very crude, approximated, generalized relativeindication of the amount of Thorium-232 and Uranium-233 that can existfor the system of FIG. 1 over time if it assumed that the neutron sourceprovides a relatively constant supply of neutrons.

As reflected in FIG. 6, at a time T_(o), before the application of anyneutrons to the system, the quantity of Thorium in the molten salt willbe at its maximum level. As neutrons begin to be applied to the system,some of the neutrons will interact with the Thorium-233 causing one ormore of the nuclear reactions discussed above. These nuclear reactionswill cause the quantity of Thorium in the molten salt to decrease overtime, as reflected by the line ²³²Th.

As also reflected in FIG. 6, by the time T₁, some of the Thorium thatwere subjected to a nuclear capture reaction will have converted toProtactinium-233 and some of those Protactinium-233 would have decayedto Uranium-233. As such, the number of Uranium-233 in the molten saltwill begin to increase over time starting at time T₁. It should beappreciated that the representation in FIG. 6 is intended to be a verycrude approximation of the relative number of Thorium-232 andUranium-233 in the molten salt and that the actual shape of therepresented curves will not necessarily be in line with the specificcurve characteristics illustrated in FIG. 6 (and can potentially becontrolled as described below).

As those of ordinary skill will appreciate, the likelihood of a nuclearreaction occurring when a specific nucleus is bombarded with a beam ofparticles having a specific incident energy level, is sometimesdescribed by a concept known as the nuclear cross-section. In general, anuclear cross-section is a quantity that expresses the extent to whichneutrons interact with particles of a given energy level. Nuclearcross-section information may be obtained through consultation of JANIS(the Java based Nuclear data Information System) provided by the NuclearEnergy Agency and accessible at https://www.oecd-nea.org/janis/

FIGS. 7A-7D provide JANIS-generated graph reflecting the cross-sectionsof various isotopes that may exist within the molten salt assembly 300of FIGS. 1A-1B.

Referring first to FIG. 7A, data reflecting the cross-section ofThorium-232 as a function of the incident energy is illustrated for boththe absorption reaction, reflected by line 2, and for the fissionreaction, reflected by line 4. Also illustrated in FIG. 7A are thefission 6 and absorption 8 cross-sections for Uranium-233 as a functionof incident energy. As the graph indicates, for Thorium-232 andUranium-233, the cross-sections for the absorption and fission reactionsvary as a function of incident energy in such a manner that thecross-section values may be considered to lie, for any incident energylevel, within one of four regions.

FIG. 7B illustrates the cross-sectional information of FIG. 3A dividedinto four regions. In the first region, designated by Roman numeral I,the absorption cross-section of Thorium-232 is comparatively largerelative to the negligible fission cross section and decreases in arelatively smooth manner with respect to changes in the incident energylevel. In that same region, the fission and absorption cross-sections ofUranium-233 exceed the absorption cross-section of Thorium-232. In theexample of FIG. 3A, Region I extends from neutron energy levels ofroughly 1×10⁻¹¹ to roughly 1×10⁻⁶ mega electron volts (MeV).

Within the second region, designated by Roman numeral II, the absorptionand fission cross-sections of Thorium-233 and Uranium-233 varysubstantially in a resonate-like manner with changes in the incidentenergy level. Over this region there are specific energy levels wherethe absorption cross-section of Thorium-232 exceeds both the fission andabsorption cross-sections of Uranium-233. It may be further noted that,over this region the absorption cross-section of Thorium-232 reaches itsmaximum value. In the example of FIG. 3A, Region II extends from neutronlevels of roughly 1×10⁻⁶ to roughly 0.007 MeV.

Within the third region, designated by Roman numeral III, the absorptioncross-section of Thorium-232 continues to remain comparatively largerelative to the negligible fission cross-section of Thorium-232. Overthat same region, the fission cross-section of Uranium-233 exceeds boththe absorption cross-section of Thorium-232 and the absorptioncross-section of Uranium-233. In the example of FIG. 3A, Region IIIextends from neutron levels of roughly 0.07 MeV to roughly 0.8 MeV.

Finally, within the fourth region, designated by Roman numeral IV, thefission cross-section of Thorium-233 is comparatively large relative toits absorption cross section, and both the fission and absorptioncross-sections of Thorium-232 vary in a roughly smooth manner withvariations in the incident energy level. Over this same region, thefission cross-section of Uranium-233 exceeds the fission cross-sectionof Thorium-233 and the absorption cross-section of Uranium-233.

The system of FIGS. 1A and 1B takes advantage of the differentcross-sections of the various atoms that will exist within the Thoriummolten salt assembly 300 to implement a novel operational and controlscheme wherein the incident energy level of the particles provided bythe particle beam source 200 are varied over time to adjust theoperating state of the molten salt system such that the energy providedby the system is predominantly generated by fission of Thorium-232 atcertain times, predominantly by fission of Uranium-233 at other times,and—potentially—fission of both Thorium-232 and Uranium-233 at othertimes. Examples of how such a novel operating method may be implementedare generally reflected in FIGS. 7A-7E.

At an initial time, the system of FIGS. 1A and 1B is operated such thatthe incident energy level of the neutrons provided by particle beamsource causes operation of the system in Region IV. This operatingregion is highlighted in FIG. 7C. This will be accomplished bycontrolling the energy level of the particles provided by the particlebeam source 200 such that they are at a sufficiently high level thatinteraction between such particles and the Beryllium within the moltensalt can result in the generation of neutrons having energy levelswithin the level of the neutrons within Region IV (i.e., over about 0.7MeV). During this period of operation, given the small quantity ofUranium-233 in the molten salt assembly 300, the energy generated by thesystem 1000 will be predominantly generated through fission ofThorium-232. However, as reflected in FIG. 7C, such operation will alsoresult in a non-trivial number of absorption reactions involvingThorium-232, which will ultimately result in the formation and buildupof Uranium-233 in the system 300.

As the number of Uranium-233 atoms in the system increases, a point willbe reached where the level of Uranium-233 is such that fission ofUranium-233 would be enough to provide the desired output power. At thatpoint, the system of FIGS. 1A and 1B 1 can transition to operate inRegion II, by adjusting the incident energy level of the provided protonbeam to a level where it will tend to cause interactions between theincident protons and the Lithium within the molten salt assembly suchthat neutrons having energy levels within Region III are generated byproton-Lithium (p, n) reactions (i.e., neutrons with energy levelsbetween about 1×10⁻⁶ to 0.007 MeV). Operation in this region, providesneutrons wherein fission of Uranium-233 is possible, but the fission ofThorium-232 as the result of neutrons generated as a result ofbombardment of particles from the particle beam source 200 isnegligible. In that same region, the neutrons within the molten saltassembly 300 will—in addition to causing fission reactions ofUranium-233, also cause absorption reactions involving Thorium-232, thusproviding a source of Uranium-233 for sustained operation. The systemcan then operate in Region III for a sustained period of time, providingthe desired power output until the number of Uranium-233 atoms in thesystem is inadequate to support the desired power output, or until otherconditions warrant a change in the operation of the system or systemshut down. Operation in this Region is reflected by the highlightedportion on FIG. 7D.

FIGS. 8A-8H illustrated examples of how the particle beam from theparticle source 200 may be directed, shaped and controlled to operatethe exemplary systems described herein within the various Regionsdiscussed above in connection with FIGS. 7A-7D.

As described above, in the exemplary systems under discussion particlebeam source 200 may be used to generate particles (such as protons)having incident energy levels of above 4.5 MeV when the generation ofneutrons having energy levels of above 0.7 MeV through a (p, n) reactionof the incident particles and Beryllium, and the direct fission ofThorium, is desired.

FIG. 8A, illustrates an example of system 1000, from a top-downperspective, that uses five Thorium fuel rods where of the Thorium fuelrods includes a Beryllium core generally as described above inconnection with FIGS. 4A-4D. In the example of FIG. 8A, the proton beamprovided by the particle beam source 200 is a solid beam spotconcentrated on the Beryllium core of the central Thorium fuel rod. Assuch the incident high energy protons will potentially collide andinteract with Beryllium within the Beryllium core, producing a (p, n)reaction that results in the generation of relatively high-energy(sometimes referred to as “fast” neutrons). These generated “fast”neutrons can then interact with a Thorium nucleus in the solid Thoriumfuel element surrounding the Beryllium core to cause a Thorium fissionreaction to occur which, in turn, will generate more fast neutrons thatcan cause further Thorium fissions to occur.

FIG. 8B illustrates a similar situation, but this time with the highenergy proton beam from the proton beam source 200 being directed to theBeryllium core of the Thorium fuel rod at the top of the image. As willbe appreciated, using the approach of FIGS. 8A and 8B, a beam spot ofparticles of the appropriate type and energy level (e.g., protons withenergy levels at or above about 4.5 MeV) provided by the proton beamsource 200 and the proton beam may be directed to the Beryllium cores ofeach of the Thorium fuel rods in the system individually. Thus, byapplying the beam for a limited period to each of the Beryllium cores, asupply of fast neutrons can be provided for each of the solid Thoriumfuel elements to maintain at least some level of Thorium fission withinthe system. This energy released by such Thorium fissions can be used tooperate the system.

FIG. 8C reflects an alternate way the system 1000 can be operated toprovide fast neutrons and to produce Thorium fissions. In the example ofFIG. 8C, the high energy particle beam from the particle beam source 200is focused at a spot within the molten salt within the molten saltassembly 300. Because at least some of the particles from the beam willhave energy levels in excess of 4.5 MeV, the particles can strike aBeryllium within the molten salt, thus causing a (p, n) reaction andproducing a fast neutron that can, in turn strike a Thorium atom withinthe molten salt or within a solid Thorium fuel element (if present) tocause a Thorium fission reaction.

FIGS. 8D and 8E illustrate still other alternate approaches forproducing fast neutrons and inducing Thorium fission reactions. In theseexamples, the beam size of the high energy particle beam from theparticle beam source 200 is adjusted such that some of the particlescomprising the high energy beam will impinge on both the Beryllium coreof one or more Thorium fuel rods (thus producing fast neutrons andinducing Thorium fissions as generally described in connection withFIGS. 8A and 8B) and others may impinge upon Beryllium atoms within themolten salt in the assembly 300 (thus inducing the generation of fastneutrons and Thorium fission as described above in connection with FIG.8C).

Still further alternate embodiments are envisioned wherein the highenergy particle beam provided by the particle beam source 200 is“strobed” from a small diameter beam spot (as generally illustrated inFIG. 8A) to a larger diameter beam spot (as generally illustrated inFIG. 8E) to vary the manner in which fast neutrons are generated.

FIGS. 8F-8H illustrate yet another alternate mode of generating fastneutrons. In this mode, the particle beam from the particle beam source200 is configured to a have a ring shape and the dimension and directionof the provided ring is varied to impinge upon the Beryllium cores ofthe Thorium fuel rods within the system and/or the molten salt withinthe assembly 300.

It should be noted that, while the above discussion focused on themanner in which fast neutrons may be generated and the fast fission ofThorium induced, operation of the system as described above will alsoresult in a number of different nuclear reactions including thegeneration of neutrons having lower energy levels (sometimes referred toas “thermal” neutrons) and the fission of any fissionable materials(Uranium-233 for example) that may exist within the assembly. This isbecause the neutrons generated within the assembly (either throughreactions involving a particle from the particle beam source 200 or asthe result of fission reactions within the assembly) will be of variousenergy levels, such that—while proton-Beryllium (p, n) reactions,proton-Lithium (p, n) reactions (generating neutrons with lower,potentially thermal, energy levels) will be occurring, as will fissionreactions of Thorium and, likely, fission reactions of Uranium-233 (ifpresent). Absorption reactions will also be occurring, as willnon-reactions where some of the generated neutrons simply escape theassembly without producing any nuclear reactions within the assembly.Moreover, neutrons generated with “fast” energy levels will tend to havetheir energy levels reduced as they pass through the materials andelements within the assembly 300 (such as the molten salt) such thatthey will become thermal neutrons that can be involved in a Uranium-233fission operation or a Thorium-232 absorption operation.

Operation of the system as described above, however, to direct highenergy particles (specifically protons) at energy levels sufficient toproduce a Beryllium (p, n) reaction will tend to promote the generationof fast neutrons and the direct fission of Thorium within the assembly300.

FIGS. 8A-8H (and primarily FIGS. 8C-8E) also illustrate how theexemplary systems described herein may be operated to promote thegeneration of thermal neutrons and Uranium-233 fission reactions. Byoperating the particle beam source 200 to provide particles (such asprotons) with energy levels of between about 2.5 MeV and 4.5 MeV, asituation may be created wherein proton-Lithium (p, n) reactions arepromoted. These reactions will tend to produce neutrons having an energylevel below the fast neutrons generated by a Beryllium (p, n) reactions.These neutrons will typically be at a level below that require forThorium fission, but at a level where they can be involved in both afission reaction involving a Uranium-233 reaction, or an absorptionreaction in which Thorium-232 is ultimately converted into Uranium-233.Thus, by operating the system 1000 in this manner, Uranium-233 fissionsmay be promoted. Again, it should be noted however that, because anyfission reactions involving of Uranium-233 or Thorium-232 that occursduring a time when the lower energy particles (such as protons) from theparticle beam source 200 are provided to the assembly 300 will producefast neutrons that can result in a fission reaction involvingThorium-232, such that fission reactions involving Thorium-232 can occurwithin the assembly 300 alongside fission reactions of Uranium-233.

Considering the above, it should be clear that the novel system 100described herein can, by adjustment of the energy level of the particlesprovided by the particle beam source 200, and by controlling thedirection and shape of the provided particle beam, be operated in mannerto promote: (i) generation of fast neutrons and the direct fission ofThorium (when high energy particles (such as protons with energy levelsabove 0.7 MeV) are provided) and (ii) generation of thermal neutronswith energy levels below 0.7 MeV and the fission of Uranium-233.

FIG. 9A illustrates one exemplary method of operating a system 1000constructed in accordance with the teachings of the present disclosure.

Over a first initial time period 902, the system will be operated froman external power source (such as a diesel generator) that will providethe input power to the particle source 200. Over this time period, thesystem 1000 can be operated to promote the generation of fast neutronsand the direct fission of Thorium through the generation of a highenergy particle beam and the direction of that particle beam to theBeryllium cores of any Thorium fuel assemblies within the system 1000.

Over this time period, the output energy level of the system can bemonitored at a step 904. Once it is determined that the energy beingproduced by the system is adequate to provide power necessary to powerthe particle beam source 200, the external power source can be removed,and the system can begin to operate without the addition of any externalpower.

After the system begins to operate without the provision of externalpower, it can continue to operate in accordance with Region IV,described above, where direct fission of Thorium is promoted and used toprovide a desired level of energy output. This is reflected by operatingstep 906. As described above, over this period, Uranium-233 will beginto be produced within the assembly.

At step 908, the level of Uranium-233 in the assembly can be monitoredand, when it is determined that the quantity of Uranium-233 in theassembly is sufficient to support the desired energy level outputthrough fission of Uranium-233, the operation of the particle beamsource 200 can be adjusted to provide particles (such as protons) of alower energy level to promote Uranium-233 fission reactions in a RegionII operation. Notably, over this region, Uranium-233 will continue to beproduced as the result of the Thorium-232 absorption reaction occurringwithin the system. Operation in this mode is reflected by step 910.

It is anticipated that the systems 1000 described herein can be operatedas described above for Step 910 for most of its operating time, forexample over a period of between 5-10 years.

Of note, in embodiments where the molten salt does not include Beryllium(for example when the molten salt is FLiNaK, the generation of fastneutrons through use of the particle beam source 200 will be throughbombardment of the Beryllium cores within the Thorium fuel rods.

In addition to producing desired energy (and generating Uranium-233 forlater use) operation of the system 1000 in accordance with a Region IVmoderation can beneficially reduce (or “burn up”) undesirable wasteelements that could otherwise build up within the assembly 300.

In general, nuclear fission reactions typically result in the productionof by-products generally known as fission products. Certain fissionreactions, such as the fission of Uranium-233 can result in theproduction of fission products in the form of actinides, includingtrans-uranium (TRU) actinides, and other long-lived fission products. Ingeneral, such by-products are undesirable because they typically emitrelatively high amounts of radiation and have relativelylong-half-lives. The handling, disposing and processing of such TRUs andlong-lived fission products is subject to various regulations andsafe-handling precautions that must be followed when dealing with suchmaterials.

Many TRU's and long-lived fission products can be broken down intoelements and isotopes that are less radioactive and/or havesubstantially shorter half-lifes such that they are safer to handle thanthe original fission products. Such TRUs and long-lived fission productscan be broken down though interactions with neutrons having certainincident energy levels, typically those on the order of the “fast”neutrons, whose generation can be promoted through operation of thesystem as described above. Thus, operation of the system in a mannerwhere generation of “fast” neutrons is promoted to reduce the amount ofundesirable waste in the system.

The exemplary system 1000 described above may be operated in variousways to reduce the amount of undesirable waste in the system. Oneexemplary operation is reflected in FIG. 9B. In this operational mode,the system can be operated as described above in connection with FIG. 9Afor most of its operating life. This operation is reflected at Step 912.Towards the end of its operating cycle, however, the system 1000 can betransitioned to operate in the manner described above, where thegeneration of fast neutrons is promoted. This is reflected in Step 914.The system 1000 could then be operated at this Step 910 until thedesired reduction of waste produces has occurred.

Note, that embodiments are envisioned where the “burn-up” Step 914 isaccomplished at a location separate from, and using a particle beamsource, different from the location at which the main running Step 912occurs. For example, embodiments are envisioned wherein a system 1000constructed in accordance with the teachings of this disclosure isoperated for a lengthy period of time at a location where energygeneration is desired and then the Thorium assembly 300 is removed andtaken to a different location where it can be bombarded with high energyparticles that result in the generation of fast neutrons for purposes ofwaste burn up.

In accordance with other embodiments, the systems 1000 described hereinmay be operated to “burn-up” waste materials during the main period ofoperation of the assembly. Such embodiments are particularly suited forapplications where the energy output demands from the system are notconstant. For example, if the system of FIGS. 1A-1B is used to generateelectricity, the demand for electricity may vary depending based ontime, day, month, or weather conditions. For example, if the system ofFIGS. 1A-1B is used to power a remote manufacturing plant, the plant maybe operational—and thus have high energy demands—only weekdays duringnormal business hours or only during certain peak months of the year. Insuch applications, after an amount of Uranium-233 has been generatedthat is sufficient to provide the desired power output, the system couldbe operated in Region II during the periods of high energy demand (suchthat the production of energy though fission of Uranium-233 ismaximized) and then be operated in Region IV during periods of lowenergy demand, such that the high-energy neutrons generated by thesystem during such operational periods can be used to burn some of theTRUs and long-lasting fission products within the system, thus reducingthe total overall waste produced by the system.

This mode of operation is generally discussed in FIG. 9C.

Referring to FIG. 9C, the system may initially be operated in accordancewhere the generation of thermal neutrons and the fission of Uranium-233is promoted as discussed above at Step 950. During these intervals, theenergy demand of the system can be monitored at Step 952. If the outputdemand of the system is not below a certain threshold (or in alternateembodiments if the output demand is above a certain threshold level),the system will continue to operate in a manner where thermal-neutronproduction and Uranium-233 fission is promoted. If the energy demand,however, is below a certain threshold (and, potentially predicted basedon data to remain at that lower level for a particular period time) theoperation of the system can be adjusted to promote the generation offast neutrons and the potential burn-up of undesired waste. This isreflected in Step 954.

While operating within Step 954, the output demands of the system can bemonitored (at Step 956) and, if they increase, the system can transitionback to operating in the manner described above in connection with Step950.

In the embodiments described above, the system 1000 is designed (and theparticle beam source 200) operated so that the system—not including theneutrons generated as a result of the operation of the particle beamsource 200—is operated in a sub-critical manner. As used herein,operation of the system in a sub-critical manner means that, if thepower to the particle beam source is removed such that the particle beamsource provides no particles to the system, the number of neutronsgenerated within the Thorium molten salt assembly 300 as the result offission or other nuclear reactions will be insufficient to sustainpermanent and on-going fission reactions within the system. As such, inthe embodiments described above, substantial nuclear fission reactionswithin the system will ultimately cease if the particle beam sourceceases to operate. This sub-critical operation of the described systemsis believed to provide a safety margin that can eliminate (or at leastsubstantially reduce) the potential for an uncontrolled series ofnuclear reactions (sometimes referred to as a “meltdown”) of theassembly 300.

In the embodiments discussed previously in this disclosure, the neutronsrelied upon to support the nuclear reactions desired for systemoperation were generated within the Thorium molten salt assembly 300.Alternate embodiments are envisioned wherein the neutrons relied uponfor operation on of the system are primarily generated outside theassembly 300.

FIG. 10 illustrates one of many alternate embodiments of the system 1000of FIGS. 1A and 1B in which fast and/or thermal neutrons desired foroperation of the system are generated outside of the molten saltassembly.

Referring to FIG. 10, the alternate embodiment includes a particle beamsource 200, a Thorium molten salt assembly 300, a heat transfer assembly400, a generator 500, and a shielding assembly 600 substantially asdescribed above. The system 1000′ also includes, however, a neutronsource target 230. As described in more detail below, in this alternateembodiment, the neutron source target 230 comprises one or more elementsthat are bombarded with the particle beam from the particle beam source220 and that, in response, generates neutrons having various desiredenergy levels.

FIGS. 11A-11F illustrate exemplary neutron source targets 230 that maybe used in connection with the embodiment of FIG. 10. For purposes ofthe following discussion, it is presumed that the particle beam source200 is as described above in connection with FIGS. 2A-2D in that it cangenerate protons having energies at two levels, where the first energylevel is above 4.5 MeV and the second energy level is between about 2.5MeV and just below 4.5 MeV.

Referring first to FIG. 11A, an exemplary neutron target source 252 isillustrated that comprises a core of neutron reflecting/shieldingmaterial (such as graphite) 254 defining an opening passing therethroughand a neutron-generating target 256 positioned within the opening. FIG.11A illustrates the cross-section of such a structure. In operation,particles from the particle beam source 200 (protons for example) enterthe core and pass through the opening on the core and strike the neutrongenerating target 256. The interaction between the high energy protonbeam and the target generates one or more neutrons that pass through theopening within the core and out of the neutron generator 252 where theycan be provided to the Thorium molten salt assembly 300 to producereactions as generally described above.

The neutron generating target 256 can take the form of any target thatincludes a material that, when struck by highly energized particles,emits neutrons. In the example of FIG. 11A the neutron generating target256 comprises a cone coated with a sufficient amount of Lithium (Li)such that the interaction with the Lithium on the cone with the incidentproton beam provided by the particle beam source 200 will cause aLithium (p, n) reaction producing neutrons at a generally thermal energylevel. FIG. 11B illustrates such a Lithium cone 256.

When the neutron generating target 256 is Lithium, the incident energylevel of the proton beam provided by the accelerator should be greaterthan about 2.4 MeV to generate the desired neutron density for operationof the system 1000′. As such, the embodiments of the acceleratordiscussed above that can generate proton beams on the order of 3 MeV canbe used with the neutron generating target of FIG. 11B.

In the embodiment of FIG. 11B bombardment of illustrated neutrongenerating target 256 with a proton beam greater than or about 2.4 MeVwill result in the generation of neutrons having an energy level ofbetween roughly about 1×10⁻⁵ and 0.07 MeV. Neutrons at such an energylevel can be applied to the Thorium molten salt system 300 to cause thereactions discussed above during periods where the generation of thermalneutrons is promoted (e.g., fission of Uranium-233).

FIG. 11C illustrates an alternative neutron generating target 258. Ingeneral, the alternate neutron target 258 is like that of target 256,but it contains Beryllium, instead of Lithium. The target 258 operatesgenerally as described with respect to the target 256, with theexception that the impingement of high energy particles on the Berylliumof target 258 will cause the generation of neutrons having a generallyhigher energy level than the neutrons generated using the Lithium target256 of FIG. 11B. In general, the neutrons generated through bombardmentof the Beryllium target of FIG. 11C will have an energy level in excessof 0.7 MeV.

In the embodiment of FIG. 11C, when the Beryllium target 258 is used theincident energy level of the protons applied to the target should be inexcess of 4.5 MeV. The various particle accelerators discussed above inconnection with FIGS. 2A-2D would be suitable to provide protons of suchan energy level.

In some embodiments of the system of FIG. 10, it will be desirable tosimultaneously provide neutrons having different energy levels and,specifically at energy levels around those using the Lithium target 256described above and the Beryllium target 258 described above inconnection with FIG. 11C. For such embodiments, it may be possible toutilize the particle beam source 200, discussed above, in combinationwith two neutron generating targets. Such an arrangement is shown inFIG. 11D, where both Lithium and Beryllium neutron targets are providedand the particle beam can be directed to one or the other target (oralternated between the two) to promote the generation of thermal or fastneutrons, respectively.

FIGS. 11E and 11F illustrate still further alternate embodiments forgenerating fast and thermal neutrons. In the example of FIG. 11E asingle neutron generating target is provided that includes uppersegments 264 formed of Lithium and a lower core 266 formed of Beryllium.In this example, a particle beam of relatively high energy levelparticles and a beam shape in the form of a spot can be directed to thelower core to generate fast neutrons and a ring-shaped beam of a lowerenergy level can be directed to the upper segments to promote thegeneration of thermal neutrons.

In FIG. 11F a neutron generating target is provided in which a Berylliumcore 272 is provided and Lithium is sputtered on to produce discreteregions 274 of Lithium containing material. In such an embodiment thesurface areas of the target will include areas of both exposed Lithiumand exposed Beryllium such that the provision of high energy particleswill result in the production of fast and/or slow neutrons. In theexample of FIG. 11F, the energy level of the incident particles can beadjusted to promote the generation of fast neutrons over thermal (e.g.,by increasing the energy level of the incident particles above 4.5 MeV)or to promote the generation of thermal neutrons over fast neutrons(e.g., by maintaining the energy level of the particles comprising theparticle beam between about 2.5 MeV and 3.5 MeV).

FIG. 12 generally illustrates the generated neutron flux levels andenergy levels when neutron generating targets such as those illustratedin FIG. 11D are used: (a) a Beryllium target is bombarded with protonshaving energy levels of approximately 4.5 MeV (reflected by thetriangles), and (b) a Lithium target is bombarded with approximately 3.0MeV protons (reflected by the diamonds).

The Figures described above, and the written description of specificstructures and functions below are not presented to limit the scope ofwhat I have invented or the scope of the appended claims. Rather, theFigures and written description are provided to teach any person skilledin the art to make and use the inventions for which patent protection issought. Those skilled in the art will appreciate that not all featuresof a commercial embodiment of the inventions are described or shown forthe sake of clarity and understanding. Persons of skill in this art willalso appreciate that the development of an actual commercial embodimentincorporating aspects of the present inventions will require numerousimplementation-specific decisions to achieve the developer's goal forthe commercial embodiment. Such implementation-specific decisions mayinclude, and likely are not limited to, compliance with system-related,business-related, government-related, and other constraints, which mayvary by specific implementation, location and from time to time. While adeveloper's efforts might be complex and time-consuming in an absolutesense, such efforts would be, nevertheless, a routine undertaking forthose of skill in this art having benefit of this disclosure. It must beunderstood that the inventions disclosed and taught herein aresusceptible to numerous and various modifications and alternative forms.Lastly, the use of a singular term, such as, but not limited to, “a,” isnot intended as limiting of the number of items. Also, the use ofrelational terms, such as, but not limited to, “top,” “bottom,” “left,”“right,” “upper,” “lower,” “down,” “up,” “side,” and the like are usedin the written description for clarity in specific reference to theFigures and are not intended to limit the scope of the invention or theappended claims.

Aspects of the inventions disclosed herein may be embodied as anapparatus, system, method, or computer program product. Accordingly,specific embodiments may take the form of an entirely hardwareembodiment, an entirely software embodiment or an embodiment combiningsoftware and hardware aspects, such as a “circuit,” “module” or“system.” Furthermore, embodiments of the present inventions may takethe form of a computer program product embodied in one or more computerreadable storage media having computer readable program code.

Reference throughout this disclosure to “one embodiment,” “anembodiment,” or similar language means that a feature, structure, orcharacteristic described in connection with the embodiment is includedin at least one of the many possible embodiments of the presentinventions. The terms “including,” “comprising,” “having,” andvariations thereof mean “including but not limited to” unless expresslyspecified otherwise. An enumerated listing of items does not imply thatany or all the items are mutually exclusive and/or mutually inclusive,unless expressly specified otherwise. The terms “a,” “an,” and “the”also refer to “one or more” unless expressly specified otherwise.

Furthermore, the described features, structures, or characteristics ofone embodiment may be combined in any suitable manner in one or moreother embodiments. Those of skill in the art having the benefit of thisdisclosure will understand that the inventions may be practiced withoutone or more of the specific details, or with other methods, components,materials, and so forth. In other instances, well-known structures,materials, or operations are not shown or described in detail to avoidobscuring aspects of the disclosure.

Aspects of the present disclosure are described with reference toschematic flowchart diagrams and/or schematic block diagrams of methods,apparatuses, systems, and computer program products according toembodiments of the disclosure. It will be understood by those of skillin the art that each block of the schematic flowchart diagrams and/orschematic block diagrams, and combinations of blocks in the schematicflowchart diagrams and/or schematic block diagrams, may be implementedby computer program instructions. Such computer program instructions maybe provided to a processor of a general purpose computer, specialpurpose computer, or other programmable data processing apparatus tocreate a machine or device, such that the instructions, which executevia the processor of the computer or other programmable data processingapparatus, structurally configured to implement the functions/actsspecified in the schematic flowchart diagrams and/or schematic blockdiagrams block or blocks. These computer program instructions also maybe stored in a computer readable storage medium that can direct acomputer, other programmable data processing apparatus, or other devicesto function in a particular manner, such that the instructions stored inthe computer readable storage medium produce an article of manufactureincluding instructions which implement the function/act specified in theschematic flowchart diagrams and/or schematic block diagrams block orblocks. The computer program instructions also may be loaded onto acomputer, other programmable data processing apparatus, or other devicesto cause a series of operational steps to be performed on the computer,other programmable apparatus or other devices to produce a computerimplemented process such that the instructions that execute on thecomputer or other programmable apparatus provide processes forimplementing the functions/acts specified in the flowchart and/or blockdiagram block or blocks.

The schematic flowchart diagrams and/or schematic block diagrams in theFigures illustrate the architecture, functionality, and/or operation ofpossible apparatuses, systems, methods, and computer program productsaccording to various embodiments of the present inventions. In thisregard, each block in the schematic flowchart diagrams and/or schematicblock diagrams may represent a module, segment, or portion of code,which comprises one or more executable instructions for implementing thespecified logical function(s).

It also should be noted that, in some possible embodiments, thefunctions noted in the block may occur out of the order noted in thefigures. For example, two blocks shown in succession may, in fact, beexecuted substantially concurrently, or the blocks may sometimes beexecuted in the reverse order, depending upon the functionalityinvolved. Other steps and methods may be conceived that are equivalentin function, logic, or effect to one or more blocks, or portionsthereof, of the illustrated figures.

Although various arrow types and line types may be employed in theflowchart and/or block diagrams, they do not limit the scope of thecorresponding embodiments. Indeed, some arrows or other connectors maybe used to indicate only the logical flow of the depicted embodiment.For example, but not limitation, an arrow may indicate a waiting ormonitoring period of unspecified duration between enumerated steps ofthe depicted embodiment. It will also be noted that each block of theblock diagrams and/or flowchart diagrams, and combinations of blocks inthe block diagrams and/or flowchart diagrams, may be implemented byspecial purpose hardware-based systems that perform the specifiedfunctions or acts, or combinations of special purpose hardware andcomputer instructions.

The description of elements in each Figure may refer to elements ofproceeding Figures. Like numbers refer to like elements in all figures,including alternate embodiments of like elements. In some possibleembodiments, the functions/actions/structures noted in the figures mayoccur out of the order noted in the block diagrams and/or operationalillustrations. For example, two operations shown as occurring insuccession, in fact, may be executed substantially concurrently or theoperations may be executed in the reverse order, depending upon thefunctionality/acts/structure involved.

The inventions have been described in the context of preferred and otherembodiments and not every embodiment of the invention has beendescribed. Obvious modifications and alterations to the describedembodiments are available to those of ordinary skill in the art. Thedisclosed and undisclosed embodiments are not intended to limit orrestrict the scope or applicability of the invention conceived of by theApplicants, but rather, in conformity with the patent laws, Applicantsintend to protect fully all such modifications and improvements thatcome within the scope or range of equivalent of the following claims.

What is claimed is:
 1. A method for generating heat in a Thoriumcontaining molten salt, the method comprising the steps of: providing amolten salt assembly comprising a main body, a lid, a tubular memberpositioned inside the main body, and a quantity of Thorium-containingmolten salt within the main body; generating a proton beam having anaverage energy level of at least 2.4 MeV; directing the proton beamthrough the lid of the molten salt assembly into the molten salt withinthe main body to induce (p, n) reactions between protons forming theproton beam and at least one material within the molten salt, whereinthe induced (p, n) reactions result in the production of at least someneutrons having an energy level of at least 0.7 MeV and wherein: atleast some of the produced neutrons interact with Thorium-232 atomswithin the molten salt to produce Thorium-233 atoms; at least some ofthe produced neutrons interact with Uranium-233 atoms within the moltensalt to fission the Uranium-233 atoms; and the fissioning of theUranium-233 atoms produces heat.
 2. The method of claim 1 furthercomprising the step of providing a molten salt within the assembly thatincludes a Lithium salt and wherein the at least one material within themolten salt that interacts with the protons from the proton beamcomprises Lithium.
 3. The method of claim 1 further comprising the stepof providing a molten salt within the assembly that includes a Berylliumsalt and wherein the at least one material within the molten salt thatinteracts with the protons from the proton beam comprises Beryllium. 4.The method of claim 1 further comprising the step of varying the shapeof the proton beam.
 5. The method claim 1 further comprising the step ofvarying the direction of the proton beam as it passes through the lid ofthe molten salt assembly.
 6. The method of claim 1 further comprisingthe steps of: providing a heat exchanger having coils positioned insidethe molten salt assembly and inlet and outlet pipes passing through themolten salt assembly; and circulating a fluid through the heat exchangerto extract heat from within the molten salt assembly.
 7. The method ofclaim 1 further comprising the steps of: controlling the average energylevel of the produced proton beam over a first interval of time suchthat an average energy level of the proton beam during the firstinterval is below 4.5 MeV; and controlling the average energy level ofthe produced proton beam over a second interval of time such that theaverage energy level of the proton beam over a second interval of timeis at or above 4.5 MeV.
 8. The method of claim 1 further comprising thesteps of: positioning impeller pumps within the molten salt assembly andoperating the impeller pumps to circulate molten salt within theassembly during a time when protons are being produced.